Method of operating alternating-current motors.



110.792, 167. PATENTED JUNE 13, 1905. L. SGHULER.

METHOD OF OPERATING ALTERNATING CURRENT MOTORS. APPLIGATION FILEDJULYfi, 1904.

2 SHEETS-SHEET 1.

Fig.1.

W/f/VESSES: INVENTOR Leo Schiiler.

ATTORNEYG No. 792,467. PATENTED JUNE 13, 1906. L. SOHULER.

METHOD OF OPERATING ALTERNATING CURRENT MOTORS.

APPLICATION FILED JULY 5, 1904.

2SHEETSSHEET 2.

Fig.2.

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M W/T/VE HVVENTOR J L S h*1 r. JMMW/ 5 C h mafia j/qrroR/vm s UNITEDSTATES Patented June 13, 1905.

LEO SOHIILIJR, OF ST. LOUIS, MISSOURI.

METHOD OF OPERATING ALTERNATING-CURRENT MOTORS.

SPECIFICATION forming part of Letters Patent No. 792,467, dated June 13,1905.

Application filed July 5, 1904. Serial No. 2153 14.

T0 at whom. it may concern.-

Be it known that I, LEO SOIIULER, a subject of the King of Prussia,Emperor of Germany, residing at the city of St. Louis, in the State ofMissouri, have invented a certain new and useful Method of OperatingAlternating-Ourrent Motors, of which the following is such a full,clear, and exact description as will onable any one skilled in the artto which it appertains to practice the same, reference being bad to theaccompanying drawings, forming part of this specification.

My invention relates to a method of operating alternating-currentmotors, and more particularly to a method of starting single-phasealternating-current motors, of the kind in which one of the members,preferably the rotor, is provided with a circuit suitably connected to acommutator or other similar means for determining the position of thepoles of such member. In another application filed by me June 17, 1901,Serial No. 212,959, I have claimed the apparatus hereinafter shown anddescribed as one of the means of carrying out my method of operatingsuch motors.

The object of my invention is to so shift the poles of one of themembers of the motor with respect to the other during the operation ofstarting and running up to normal speed that the motor will start andattain such speed under the most favorable conditions for producing theproper torque and with a minimum consumption of current. To this end Iprovide the motor with a subdivided field-winding, the organization orthe electrical connections of which may be modified to suitably vary theangular displacement of the poles of the field with relation to those ofthe armature.

In starting motors of the general type above referred to I have foundthat an angular displacement of substantially fifteen electrical degreesbetween the poles of the field and those of the armature is mostadvantageous for producing the static torque desirable for bringing therotor to a certain speedsay substantially one thousand revolutions perminute and that after such speed has been attained the rotor is bestbrought up to normal running speed by reducing such angular displacementto substantially five degrees, though, of

course, these proportions and values may be varied without departingfrom my invention.

In the accompanying drawings, which show slightly-differing forms ofmotor adapted for carrying out my method, and in which like charactersof reference refer to similar parts in the different views, Figure 1 isa diagrammatic representation of the field and armature windings of suchmotor; and Fig. 2 is a diagram of a motor embodying my invention, butdiffering slightly from the form shown in Fig. 1.

Referring first to Fig. 1, 10 indicates the core of the induced orrotary member or armature of the motor; 11, the armature-winding,hereshown as of the continuous type; 12, leads from said winding connectingthe same with the segments of a commutator 13; 14, brushes resting onsaid commutator, and 15 a conductor connecting said brushes together inlocally-closed circuit. These parts are of usual and well-knownconstruction and operation and are therefore not more particularlydescribed herein. Thcy may be varied widely from the form here shownwithout departing from my invention. 16 and 1'7 indicate the mainconductors supplying current to the field of the motor. 18 a switchadapted to connect the conductor 17 to either of the contacts 19 and 20.The main field-winding or circuit of the motor is divided into twodiametrically opposite sections 21 and 22. One end of the section 21 isconnected, by means of the wire 23, with the contact 19. Its oppositeend is eonnected,by means of the wire 24,with one end of the section 22,the opposite end of which last-mentioned section is connected to themain conductor 16. The field of my motor is provided with an auxiliarywinding or circuit divided into two sections 26 and 27. The section 26has one of its ends connected to the wire 23,and its opposite end isconnected, by means of the wire 28, with one end of the section 27, theopposite end of which is connected with the contact 20.

Referring now to Fig. 2, it will be seen that the armature there showndiffers from the armature shown in Fig. 1 only in that the armature atFig. 2 is provided with a short-circuiting ring 30, which is adapted tobe clamped upon the segments of the commutator 13 in any suitable mannerafter the motor has attained normal running speed. This device isalready well known in the art and its construction and operation neednot be further described herein. The field of the motor shown in Fig.2diifers from that of Fig. 1, however, in that it is provided with twoauxiliary fieldwindings. The sections 21 and 22 are connected in seriesby means of the wires 23 and 24 between the contact 19 and the main line16, as described in connection with Fig. 1. 32 and 33 are the sectionsof an auxiliary winding. One end of the section 33 is connected to thecontact and its other end is connected, by means of a wire 34,with oneend of the section 32, the other end of which is connected, by means ofa conductor 35,with a third contact 36 within reach of the switcharm 18and situated between the contacts 19 and 20. A second auxiliary windingis composed of the sections 38 and 39. One end of the section 38 isconnected to the conductor 23 and its opposite end by means of theconductor 40 is connected to one end of the section 39, the other end ofwhich is connected to the conductor 35.

In practicing the method of my invention and referring first to Fig. 1it is evident that when the brushes are in the position there shown thefield generated by the currents induced in the armature of the motorwill have the axis of its poles substantially coincident with the dottedline A A. When the motor is started from rest under load, the switcharm18 is placed upon the contact 20. It is evident that under suchcircumstances the current from the main line will pass in series throughthe sections 21 and 22 of the main winding and 26 and 27 of theauxiliary winding. This generates a magnetic field the poles of whichare substantially coincident with the dotted line B B, thus bringingabout an angular displacement of substantially fifteen electricaldegrees between the poles generated by the field-winding and the polesgenerated by the induced currents in the armature. This displacement Ifind very advantageous, as above explained, for producing a statictorque mostfavorable for starting the motor and for bringing it to acertain speed-for instance, about one thousand revolutions per minute.When this speed has been attained, the switch 18 is thrown to thecontact 19 and the auxiliary sections 26 and 27 are cut out of circuit,leaving in active operation only the sections 21 and 22 of the mainwinding. This gives rise to a shifting of the poles of the field of themotor until their axial line coincides substantially with the dot tedline D D, (intermediate the lines A A and B B,) and such poles areangularly displaced substantially five electrical degrees from thearmature-poles. This displacement produces torque in the direction inwhich the motor has started to rotate and places the motor in favorablecondition for running up from the one thousand revolutions per minutealready attained to a normal running speed of, say, fifteen hundred(1500) revolutions per minute.

Referring now to the practice of my inven tion in connection with thedevice shown in Fig. 2, it is thought that the same will be readilyevident. hen the motor starts from rest, with the switch 18 on thecontact 20, the main winding and both of the auxiliary windings 32 33and 38 39 are connected in series in the circuit and are inactiveoperation, thus generating a magnetic field the axis of whose poles isindicated by the dotted line B B, which line is displaced substantiallyfifteen (15) electrical degrees from the axial line A A of thearmature-poles. obtained the desired speed under these conditions theswitch 18 is shifted to the contact 36. This excludes the auxiliarywinding 32 33 from circuit and shifts the axial line of the poles of thefield to substantially the position of the line C C, intermediate thelines B B and A A and substantially ten (10) elec-. trical degreesdisplaced from the axial line A A of the armature-poles. When the speedof the motor has been suitably decreased under these conditions, theswitch 18 is shifted to the position shown in Fig. 2that is, to contact19. This excludes the remaining auxiliary winding 38 39 from thecircuit, leaving only the main winding in active operation. A field isthus generated which has the axial line of its poles substantiallycoincident with the dotted line D D, intermediate the axial line A A ofthe armature-poles and the former positions B B and C C of thefield-poles and displaced angularly substantially five (5) electricaldegrees from the axial line A A of the armature-poles. In this conditionthe motor is allowed to run up to normal speed. When such speed has beenobtained, the short-circuiting device 30 is moved by any suitable meansinto contact with the segments of the commutator 13, thusshort-circuiting said commutator, after which the motor will run in theordinary way as an induction-motor. It is evident that as I preferablyshort-circuit the individual coils of the motor-armature when normalrunning speed is attained, thus allowing the motor to run as aninductionmotor proper, the motor is not intended to or adapted forrunning above synchronism when the short-circuiting is employed.Induction-motors proper of this type, in which a large number of shortcircuits are introduced into the winding, run below synchronism whennormal running speed is attained.

Having fully described my invention, what I claim as new, and desire tosecure by Letters Patent of the United States, is-

1. Themethodofoperatingalternating-cur- .rent motors, which consists inproducing a given angular displacement between the poles After the motorhas 1 of the respective members to produce torque in one direction,shifting the poles of one of said members to a second position producingtorque in the same direction, and changing the circuits of the other ofsaid members before synchronous speed is exceeded.

2. The method of operating alternating-current motors, which consists inproducing a given angular displacement between the poles of therespective members at starting to prod uce torque in one direction,shifting the poles of one of said members after said motor has startedto a second position producing torque in the same direction, and thenshort-circuiting the other of said members before synchronous speed isexceeded.

3. The method of operating alternating-current motors, which consists inproducing a given angular displacement between the poles of therespective members at starting to produce torque in one direction, thenshifting the poles of one of said members after said motor has startedto a second position producing torque in the same direction, and finallyshortcircuiting the other of said members when normal running speedunder load is attained and before synchronism.

In testimony whereof I have hereunto set my hand and afiixed my seal inthe presence of tWo subscribing witnesses.

LEO SGHULER. [n s.]

Vitnesses:

FRED HENKE, D. C. BETJEMAN.

